Switching devices are used in electrical engineering to switch electrical currents in different kinds of circuits. Switching of the power circuit of an electric motor requires, depending on the implementation, switching of one or three current phases. Because there may be relatively high currents involved, the generic class of switching devices comprises devices such as contactors, circuit breakers and overload relays. Each of these devices has means adapted to perform different aspects of switching-related functions. But in general, a switching device comprises switching means for switching at least one current phase between responsive current phase input and responsive current phase output, such as at least one movable contact piece and responsive stationary contact pieces for each phase, or corresponding electronical switching means.
It is desirable to be able to remotely monitor the actual status of a switching device, especially of its switching means, or to remotely change operation of a switching device, especially of its switching means. Particularly desirable this will be when switching devices are installed in a group thus comprising a plurality of switching devices there then being a larger number of power circuits to switch or a larger number of switching devices along one power circuit.
With an increasing number of switching devices the time and effort to manually monitor or control the switching devices increases so much that it easily becomes to a burdensome task.
To enable remote monitoring or changing of operation of a switching device, there are currently some implementations on the market, such as SIMOCODE® of the present applicant. The structure of the current implementation is schematically illustrated in FIGS. 1 and 2.
FIG. 1 shows a prior art gateway 110 connected to a group comprising four switching devices 120. A switching device 120 comprises switching means, known as such, for switching at least one current phase between responsive current phase input such as L1, L2, L3 for three phases and responsive current phase output such as T1, T2, T3 for three phases. Furthermore, the switching device 120 is suitable for switching electrical current of a power circuit of an electric motor.
FIG. 2 shows the system of FIG. 1 when the first communication system interface 112 of the gateway 110 has been connected to a first communication system 240, preferably via a responsive communication system interface 212 of the first communication system 240. The second communication system interface 116 of the gateway 110 is connected to a communication system interface 116 of a switching device 120 so that the gateway 110 and the switching device 120 may communicate to the second communication system 241. Further switching devices 120 may be connected to the second communication system 241 through their responsive communication system interfaces 116. The connections between the switching devices 120 and the second communication system 241 may be carried out by using bridging elements 115 connected to responsive second communication system interfaces 116 of the switching devices 120.
An on-site control device 230 may be provided, connectable to the second communication system 241 through a special adapter 235. The on-site control device 230 may be used for testing purposes, especially when system has not yet been connected to the first communication system 240, over which it could be monitored and controlled by the control system 200.
The gateway 110 takes care of routing messages from the second communication system 241 to the first communication system 240 which has a larger bandwidth than the second communication system 241. In this manner, the switching devices 120 can be kept as simple as possible, in particular because the second communication system 241 can be a very basic one requiring very little processing power at the processing units □C of the switching devices 120.